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// Encog(tm) Core v3.3 - .Net Version
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// Copyright 2008-2014 Heaton Research, Inc.
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using Encog.Engine.Network.Activation;
using Encog.ML.Data;
namespace Encog.Neural.Error
{
    /// <summary>
    /// An error function.  This is used to calculate the errors for the
    /// output layer during propagation training.
    /// </summary>
    public interface IErrorFunction
    {
        /// <summary>
        /// Calculate the error.
        /// </summary>
        /// <param name="af">The activation function used at the output layer.</param>
        /// <param name="b">The number to calculate the derivative of, the number "before" the activation function was applied.</param>
        /// <param name="a">The number "after" an activation function has been applied.</param>
        /// <param name="ideal">The ideal values.</param>
        /// <param name="actual">The actual values.</param>
        /// <param name="error">The resulting error values.</param>
        /// <param name="derivShift">The amount to shift af derivativeFunction by</param>
        /// <param name="significance"> Weighting to apply to ideal[i] - actual[i]</param>
        void CalculateError(IActivationFunction af, double[] b, double[] a,
                IMLData ideal, double[] actual, double[] error, double derivShift,
                double significance);
    }
}
